|The Prometheus Project, Part 2|
|Season 4, Episode 15 (75)|
|The Prometheus Project, Part 1||Not Easy|
PART 3 OF 7: DECISIONS, DECISIONS- As the Birds are put on the defensive, the synthetics prove to be the toughest adversary they've yet faced. Malcolm Merlyn tries to reconnect with Thea Queen as they evade P.R.O.M.E.T.H.E.U.S.. Laurel Lance and Nyssa Raatko have a heart-to-heart while Tess Luthor manipulates a captive Carrie Cutter and Ray Palmer.
- Katie Cassidy as Laurel Lance/S.I.R.E.N.
- Katrina Law as Nyssa Raatko
- Jessica de Gouw as Helena Bertinelli/H.U.N.T.R.E.S.S.
- Willa Holland as Thea Queen/Speedy
- Katie McGrath as Tess Luthor
- Chyler Leigh as Alexandra Danvers
- with Amy Acker as Brainiac
- and Katheryn Winnick as D.I.S.C.O.R.D.
Special Guest StarsEdit
- Michael Rosenbaum as Lex Luthor (Earth-30)/Lex Luthor (Earth-10)
- David Ramsay as John Diggle
- Audrey Marie Anderson as Lyla Diggle
- Colin Donnell as P.R.O.M.E.T.H.E.U.S.
- Kristin Kreuk as Evelyn Langstrom
- Deborah Ann Woll as Andrea Beaumont
- Sofia Boutella as Mercy Graves
- with John Barrowman as Malcolm Merlyn
- and Brandon Routh as Ray Palmer/ATOM
- Antagonists: Lex Luthor (Earth-10), Mercy Graves, Tess Luthor,S.I.R.E.N., P.R.O.M.E.T.H.E.U.S., Leticia Luthor
- Title meaning: Laurel, Nyssa, and Kara's meditations on worth and redemption
- This is the fourth midseason finale.
- This is the 4th midseason finale to feature Laurel, Thea, Carrie, Ray, and Malcolm.
- This is the 2nd midseason finale to feature John, Kara, and Talia.
- This is the first midseason finale to feature Nyssa Raatko, E10 Lex, Tess, Mercy, Alexandra, SIREN, PROMETHEUS, and DISCORD.
- This is the first midseason finale to not feature Lena and Nyssa al Ghul. It's also the only midseason finale in which Nyssa al Ghul is absent.
- This episode takes place on January 19, 2020.